On the origins of the Roman names of the planets.

Given the choice of many of the images on this website, I will dedicate the first blog post to a hypothesis that I like to play around with.

I have looked for some time for etymological roots of the names of the planets as we know them in English (via Latin). I have yet to find anything particularly satisfying. It seems odd to me not to give some attention to the region of the world that is home to the greatest collection of ancient stellar observatories – northwest Europe, in particular what were, prior to Roman conquest, Celtic regions. Circular henges, which likely served as observatoria having the feature of an artificial, uniform horizon, date back up to 6000 years ago, long before Mesopotamian astrological tradition.

Recent archaeological work supports a model for western Europe of cultural continuity through the Mesolithic, and perhaps even the Paleolithic periods, and Celtic has been proposed to be an indigenous development along the Atlantic Fringe of Europe. It has long been acknowledged to have a significant substratum which is pre-Indo European, perhaps Hamitic in origin. In this light, we might look to the surviving Celtic languages for some transmission of the ancient astronomical/astrological understandings that the megalithic culture had amassed.

My proposition with this is that when we can find roots for the names of planets that have both a broader range of pertinent meaning in another language, and can be further tracked back by breaking them into compounds that themselves shed light on the fundamental associations that we have with those planets, that we are likely closer to the original linguistic source for that name. I’m no scholar of Latin, or of Gaelic for that matter, but it seems to me that there is much more meat to these etymologies than can be found for their Latin equivalents.

* all words taken from eDIL online dictionary of middle and old Irish: www.dil.ie *


Mercuir in Old Irish. Possibly composed of the roots mer, meaning that which is nimblest or fastest, and cuir, a word implying a circuit or circle, cognate with the French cours, a course. This would well reflect the astronomical reality of Mercury being the swiftest moving planet, other than the Moon.


Uenir in Old Irish. The Latin is perhaps taken from the word ben, which means woman or wife. In the vocative case, this becomes a bhen, pronounced “a ven.” We can see the Latin termination -us added to the Gaelic root. This fits neatly with the idea of Venus being a feminine planet in astrology. Venus in astrology is associated with the colour green, which is colour is called Uaine in Gaelic.


In Gaelic, the planet Mars is called Mairt (pronounced mayrsht). The likely root is mart, having several meanings: the month of March (in which we see only the dropping of the final t sound from the Gaelic pronunciation); death, slaughter, massacre; a cow killed for its meat. We have here clear associations with Mars as the planet which rules violent action. In addition, one could make the connection between Mars’ rulership of Scorpio as the time when a young male cow would be killed for its meat.


In connection with Mars, the root here is perhaps the gaelic Àr, also meaning slaughter, as well as Ar, meaning ploughing. Both of these connect with Aries as being under the rulership of Mars, and the beginning of Spring when the land is again ready for tillage (well, depending on local temperature).


As the Romans called this planet Jove, we can look for the root in the gaelic name for the planet, Ioib. I am unable to find any meaning to Ioib, however. Jupiter, believed to be from the compound Deus Pater, could well be from the Gaelic Ioib Athair, the latter word meaning Father as well.


In Gaelic, the name for Saturn is Sathairn. Likely a compound of the Gaelic sàith, meaning full, or abundance, or saith, meaning wealth, and aran, meaning bread. This fits with the Roman conception of Saturn as the god of agriculture, and ruler of the golden age in which the Earth’s bounty was plentiful. Of note is that in modern Scottish Gaelic, sath means bad.

In pagan times, a deity called Crom Cruach was worshipped by the Gaels. He is an agricultural/fertility figure. Crom means crooked or bent, and Cruach means a stack, generally of harvested grain or peat. Crom Cruach was associated with sacrifices of the first born in exchange for good harvest, and in this we see some parallel with the Greek Cronos, not to mention the phonetic similarity between Crom and Cron(os). In horary astrology, people signified by the planet Saturn are frequently seen to have a ‘crooked’ or stooped posture.

The Moon

Luna in Latin, the likely root is the Gaelic luain* meaning restless, and its derivative luaineach, meaning changeableness, inconstancy, activity, that which moves, volatility.

* this is found in modern Scottish Gaelic dictionaries, the eDIL dictionary only has an entry for lùaimnech, which carries the same meanings as luaineach.

Here we see the essential character of the Moon as both being the most mobile of the planets, and the most visibly inconstant. It is interesting to note the while the word Luain is used in Gaelic to mean the moon (or Monday, as Di-Luain), there are other words that are more commonly used for the Moon, Re being one of the older common names. Note the connection with Rhea, mother of the Gods in Greek mythology, and whose symbol was the Moon.

The Gaelic word for star is reult or realt, a compound of re and allt, meaning a height. The stars are thus the high moons.

The Sun

It is difficult to tease appart the Latin Sol from the Gaelic Sol, both meaning Sun. In Gaelic we have solus, meaning light, bright, perhaps as the root of the Latin solacium and English solace, meaning comfort. The Gaelic solus is itself a compound of so, meaning good or excellent, and lés, meaning light or radiance. We have thus the idea of the Sun as the Good Light. Latin and Gaelic also share the meaning of sol as foundation, or ground, as the Sun is the foundation of all Life.

Of interest is that the more common word for Sun in Gaelic is Grian. This word also appears in Old Irish as figuratively meaning the foundation or basis of something. Of note is that another name for Apollo in the Greek tradition (who is associated with the Sun) is Gryneus. Apollo was traditionally believed to retire to an island in the far West, perhaps suggestive of Ireland.

I have a feeling that we should be looking more at this ancient language for some insights into the very early astrological tradition. It is not too surprising that ancient Celtic languages would have exerted an influence on Latin terminology. What is more surprising are the connections with Greek mythology. It should be realized, however, that the ancient Druids were held in very high esteem by Roman as well as Greek philosophers. There is a companion piece of sorts to this post, which looks at the old Gaelic alphabet, and some of the links between it and the alphabet, as well as settlements, of the Phoenicians.